1. Field of the Invention
The present invention relates to a method and apparatus for characterizing and estimating the parameters of a person's heartbeat for the purpose of authenticating a biometric signal. More specifically, the present invention relates to methods and apparatus for characterizing and estimating the parameters of a heartbeat signal that is substantially unique to a person in order to permit the person to use the heartbeat signal as a biometric marker to activate a device, participate in a transaction, or identify him or herself.
2. Description of Related Art
The computer industry has recognized a growing need for sophisticated security systems for computer and electronic devices. The security systems are used to prevent unauthorized use and authenticate or identify individuals through electronic means. The biometric authentication industry has developed in response to this need. Biometrics is the measurement of quantifiable biological traits. Certain biological traits, such as the unique characteristics of each person's fingerprint, have been measured and compared and found to be unique or substantially unique for each person. These traits are referred to as biometric markers. The computer and electronics industry is developing identification and authentication means that measure and compare certain biometric markers with the intention of using the markers as biological “keys” or “passwords.”
Biometric markers presently used by the industry for authentication and identification include the use of measurements of unique visible features such as fingerprints, hand and face geometry, and retinal and iris patterns, as well as the measurement of unique behavioral responses such as the recognition of vocal patterns and the analysis of hand movements. The use of each of these biometric markers requires a device to make the biological measurement and process it in electronic form. The device may measure and compare the unique spacing of the features of a person's face or hand and compare the measured value with a value stored in the device's memory. Where the values match, the person is identified or authorized.
Several types of technologies are used in biometric identification of superficial anatomical traits. For example, biometric fingerprint identification systems may require the individual being identified to place their finger on a visual scanner. The scanner reflects light off of the person's finger and records the way the light is reflected off of the ridges that make up the fingerprint. Hand and face identification systems use scanners or cameras to detect the relative anatomical structure and geometry of the person's face or hand. Different technologies are used for biometric authentication using the person's eye. For retinal scans, a person will place their eye close to or upon a retinal scanning device. The scanning device will scan the retina to form an electronic version of the unique blood vessel pattern in the retina. An iris scan records the unique contrasting patterns of a person's iris.
Other types of technologies are used for biometric identification of behavioral traits. Voice recognition systems generally use a telephone or microphone to record the voice pattern of the user received. Usually the user will repeat a standard phrase, and the device compares the measured voice pattern to a voice pattern stored in the system. Signature authentication is a more sophisticated approach to the universal use of signatures as authentication. Biometric signature verification not only makes a record of the pattern of the contact between the writing utensil and the recording device, but also measures and compares the speed of the writing and pressure applied in the process of writing.
Each of the prior art systems has a number of disadvantages. For example, fingerprint databases may raise significant privacy issues for those whose information is entered in the system. Hand and facial geometry recognition systems may require large scanners and/or expensive cameras. Voice recognition devices have problems screening out background noise. Signature recognition devices are subject to variations in the behavior of the individual. Retinal devices may require users to place their eye close to or on a scanning device, exposing the user to potential infection.
Another disadvantage of the prior art to biometric authentication is that there are only a limited number of biometric markers that are practical for implementing in computer and electronic devices. Biometric patterns used in the prior art to authenticate a person that are completely unique to each person may have only minute differences; the patterns that distinguish one person from another person may be subtle. Measuring and authenticating such patterns may require a high degree of electronic sophistication to read and differentiate between the various unique aspects of the biometric marker. If the biometric marker is used to identify an individual from a large group of individuals, the computer memory storage and processing capability may also have to be sophisticated, and therefore, may be expensive.
Another disadvantage of prior art is that with relatively few truly unique biometric markers, it is likely that use of those markers, such as a fingerprint, would be widespread. The widespread use of just one or two types of markers increases the likelihood that an unauthorized person could, by chance or otherwise, be improperly granted access. If an unauthorized person were improperly given access, that individual may have access to numerous secured devices or accounts. This is the same problem that exists when a person chooses the same password for all his accounts or electronic devices and the password is stolen.
U.S. Pat. No. 4,537,484 to Fowler et al. discloses a fingerprint imaging apparatus for use in an identity verification system. The system uses light, which is reflected off the finger through a system of mirrors to a linear photo diode ray. The fingers are rotated mechanically in order to scan the entire fingerprint.
U.S. Pat. No. 4,544,267 to Shore discloses an identification device that uses a beam of collimated light to scan the fingerprint. The light beam is then imaged onto a linear ray of photo-responsive devices. The information is processed to provide a set of signals containing fingerprint information.
U.S. Pat. No. 4,699,149 to Rice discloses a device for detecting the position of subcutaneous blood vessels such as by using the reflection of incident radiation off of a user's skin. The measured pattern is then compared with a previously determined pattern to verify the identity of the user.
U.S. Pat. No. 4,728,186 to Eguchi et al. discloses another method for detecting data points on uneven surface such as a finger, namely a fingerprint, using a light source illuminating the uneven surface through a transparent plate.
U.S. Pat. No. 4,784,484 to Jensen discloses an apparatus for automatic scanning of a fingerprint using an optical scanner. The user slides his finger across a scanning surface and an optical scanning system generates an electrical signal as a function of the movement of the finger across the optical scanning surface.
U.S. Pat. No. 5,073,950 to Colbert et al. discloses a method and apparatus for authenticating and verifying the identity of an individual based on the profile of a hand print using an optical scanner.
U.S. Pat. No. 5,077,803 to Kito et al. discloses a fingerprint collating system employing a biological detecting system.
U.S. Pat. No. 5,088,817 discloses an apparatus for detecting and identifying a biological object by projecting a light beam onto the object and detecting the reflective light using an optical detector. The change in the wave length characteristics of the light beam can be compared to a previously determined pattern.
U.S. Pat. No. 5,230,025 discloses a system for generating data characteristics of a rolled skin print using an optical device that can convert reflective light beams into an electronic signal and generate digital data representative of the image of the skin print.
U.S. Pat. No. 5,335,288 to Faulkner discloses a biometric measuring apparatus that uses silhouette and light images to measure a person's hand features. The features are converted to electronic data and stored and later compared for identification purposes.
Some biometric authentication systems combine biometric measurements with conditioned behavior such as signature writing styles and voice patterns or intonations. For example, U.S. Pat. No. 5,103,486 to Grippey discloses a signature verification system utilizing a hand held writing implement that produces data regarding a person's fingerprint pattern and their hand written signature.
Other biometric authentication systems include means for verifying physiological activity. These means for verifying physiological activity are primarily to prevent an unauthorized person from using dead tissues as a means for circumventing the authentication process. For example, U.S. Pat. No. 5,719,950 to Osten et al. discloses a personal biometric authentication system wherein inherently specific biometric parameters are measured and recognized and at least one non-specific biometric parameter is recognized and compared with physiological norms. Likewise, U.S. Pat. No. 5,727,439 to Lapsley et al. discloses an antifraud biometric scanner that determines whether blood flow is taking place in the object being scanned and whether such blood flow is consistent with that of a living human.
It would therefore be advantageous to provide a method and apparatus for biometric authentication and activation that does not exclusively rely upon the measurement of superficial anatomical structure and/or behavioral responses. It would also be advantageous to provide a biometric authentication system that is relatively inexpensive and portable. It would be a further advantage to provide a biometric authentication system that can use, but does not require, unique biometric markers. It would also be advantageous to provide a method and apparatus for biometric authentication that can use a single technology to measure multiple, varied biometric markers.